1. Technical Field
The present invention relates to a test apparatus and a calibration method of a test apparatus. More particularly, the present invention relates to a test apparatus that tests a device under test and a calibration method for adjusting a duty ratio of a test signal.
2. Related Art
In recent years, the speed of semiconductor circuits and the like has been greatly increased. Along with this, an increase in the speed of test apparatuses testing the semiconductor circuits and the like is also desired, leading to manufacturing of test apparatuses that generate test signals of multiple GHz. Because the test signals of such test apparatuses are high frequency, it is necessary to adjust the duty ratio of the test signals with high precision. To adjust the duty ratio of the test signals, beginning by measuring the duty ratio of the test signal is considered.
For example, the duty ratio of the test signal can be measured by bringing a probe into contact with an output pin of the test apparatus to measure each edge timing of the test signal. In a case where a plurality of output pins are disposed on the test apparatus, the duty ratio of the test signal from each output pin can be measured by sequentially bringing the probe into contact with each output pin.
However, in a case where the duty ratio of a test signal of multiple GHz is measured, the edge timing must be measured with an error range of multiple ps, which requires use of a timing measurer having extremely high precision or the use of a probe with little signal degradation. Because of this, the cost of testing undesirably rises.
Furthermore, a multitude of output pins are disposed on the test apparatus according to the number of pins of the semiconductor circuit or the like. Because of this, the testing time is undesirably increased when the probe is sequentially brought into contact with each pin to measure the duty ratio of the test signal. It should be noted that Japanese Patent Application Publication No. hei11-306688 is listed herein as a prior art document.